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MG MGF Technical - hydrogas suspension and hot weather

My car is lowered and stiffened by Tech Speed. However, at the last Sprint I did at Goodwood I noticed the car looked strangely high. IT was very hot that day. Can this cause the suspension of the car to pump itself up? Or have I broken something? The car looks a bit like those Fs you see around too pumped up!
m hanson

Temperature change does affect the ride height on an MGF. At 17°C on a standard setup the ride height should be 368mm + or - 10mm. My car's also lowered, but rather than measure the height with a tape I tend to use the "two finger" method (index and middle finger fit between the wheel arch and tyre. I've recently invested in a hydragas pump so that I can keep it at this height during both the heat of the summer and the cold of the winter.
David Clelland

My car (Techspeed suspension and lowered) normally sits at around the 1 to 2 finger mark as DC describes. However, today, the record July temps meant that it was sitting with at around 2 to 3 finger height. 80 miles hurtling around the SW circuit at Bedford Autodrome didn't help of course - the inside of my crash helmet was like a swimming pool (yuk!)

Dave Livingstone

I am having the reverse problem, set up for summer by the two finger method my car is now sitting speed hump low . The temp is averaging 12c. Can't wait for spring!.
Andrew Regens

Hydragas - loved by owners, hated by Motorsport Race teams; its main problem is lack of consistency with temperature, which results in significant changes in trim heights - and therefore in camber and static toe angles...

Nothing to worry about though - 'they all do that sir'
Rob Bell

Hi Rob - your brakes lasted well enough to get home then :-)
Dave Livingstone

Rob and Dave thanks. Thought I was going mad. My car sounds like its doing exactly what Davids did. Resulted in a pretty poor time at Goodwood (6 seconds a lap slower than my best) as well as a spin at Lavant when I just missed going backwards into the tyre wall. Am doing Prescott on Saturday and if my cars still a "cherry picker" (its going to be scorching apparently) I'll take it slowly! Also will try and get my best run in first!
marc h

Ambient temperature and lower engine power probably did that to you Marc - unless you found the car handling badly? Other aspect is tyre performance. I'd be surprised if you over heated the tyres on a single lap of Goodwood, but slippy tyres certainly won't help lap times!!!
Rob Bell

Rob, it handled terribly, very jittery! see the attached photo of me exiting the chicane (taken by John Neighbour)http://www.johnneighbour.com/goodwood_sprint_34.htm

Look how high the car is on BOTH sides! Doubt the heat was enogh to lower my time so dramaticaly - maybe Im just pants this year!
marc h

Difficult to see how high to be honest Marc from that angle? But Goodwood is a power circuit, IMO. A couple of horses go a long way due all those corners you take at full throttle, not to mention that long straight...

Shame about the handling though. Is it okay now??
Rob Bell

Started the day at Prescott with "2 fingers" ended up with 4!! Looks a bit like an off roader now....
marc h

Yup - that sounds about right. Had exactly the same happen to be at Bedford on Wednesday Marc. Heat and gas leads to expansion - which results in a higher ride height with Hydragas...
Rob Bell

BTW this happens even in cold weather, but usually the change in ride height is not quite as pronounced.
Rob Bell

This thread was discussed between 19/07/2006 and 24/07/2006

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